Do Laboratory Blood Tests Change Medical Care in Patients Hospitalized with Community-Acquired Pneumonia?

Background and Objectives: The prevalence of inappropriate laboratory testing is believed to be high, but only a limited number of studies have reviewed medical charts to determine whether tests impact medical care. Materials and Methods: From the electronic database, we selected 500 consecutive patients with community-acquired pneumonia who were hospitalized between January 2020 and October 2021. We excluded eight patients who had COVID-19, but were not identified in the database, and were only identified after chart review. To assess the impact of tests on medical care, we conducted a thorough review of the patients' charts. Results: The age of the patients was 78 ± 16 years, with 42.3% female (n = 208) hospitalized for a median of 4 days (25-75%, 3-6 days). There were 27957 laboratory test results during 2690 hospital days (10.4 tests per day of hospitalization). Of the 2997 tests carried out on admission 5.7% (n = 170) resulted in changes of medical care in 34.5% (170/492) of the patients, nearly all from the results of electrolytes, renal function tests, and serum glucose measurements. Tests that did not lead to any decision on medical care included 75.8% (7181/9478) on admission and 86.0% (15,898/18,479) on repetitive testing, i.e., repetitive testing accounted for 68.9% (15,898/23,079) of tests that did not change medical care. By excluding tests that did not change medical care, the overall testing rate would decrease by 82.6% (23,079/27,947), and from 10.4 tests per day to 2.1 tests per day. Conclusions: We conclude that the estimate of the overuse of laboratory testing, which includes all testing that does not change patient care, is much higher than reported using other methodologies. Most of the overuse was from repetitive testing that included unnecessary testing in patients without admission test results that changed medical care. Further investigation is needed to determine if these findings can be applied to patients with diverse health conditions and in different healthcare settings.